Index: tests/test.py
===================================================================
--- tests/test.py	(revision a5121bff2d239413034fc4cc466f9e5b15eebd1b)
+++ tests/test.py	(revision 455a7d5b684d35263cb198930cc33e3f035b52ff)
@@ -98,5 +98,10 @@
 	parser.add_argument('tests', metavar='test', type=str, nargs='*', help='a list of tests to run')
 
-	options =  parser.parse_args()
+	try:
+		options =  parser.parse_args()
+	except:
+		print('ERROR: invalid arguments', file=sys.stderr)
+		parser.print_help(sys.stderr)
+    		sys.exit(1)
 
 	# script must have at least some tests to run or be listing